Enable methods on strings

Summary:
This diff turns on methods on strings for Zoncolan by adding an option to enable the methods for unit tests, removing some checks that would skip the new string class, and adding a couple new models

Must be landed after D92323232

Reviewed By: marat-turaev

Differential Revision: D92170162

fbshipit-source-id: 5724350f009af502b0a4725f394cd6002af6e081

Author: Sheila Jimenez

hphp/hack/src/hh_single_ai.ml

@@ -57,6 +57,7 @@ let parse_options () =
   in
   let allowed_fixme_codes_strict = ref None in
   let allowed_decl_fixme_codes = ref None in
+  let ignore_string_methods = ref true in
   let options =
     [
       ( "--extra-builtin",
@@ -73,6 +74,9 @@ let parse_options () =
         Arg.String
           (fun s -> allowed_decl_fixme_codes := Some (comma_string_to_iset s)),
         "List of fixmes that are allowed in declarations." );
+      ( "--enable-string-methods",
+        Arg.Unit (fun () -> ignore_string_methods := false),
+        " Enable methods on string primitive types" );
     ]
   in
   let options = Arg.align ~limit:25 options in
@@ -107,6 +111,7 @@ let parse_options () =
         allowed_decl_fixme_codes =
           Option.value !allowed_decl_fixme_codes ~default:ISet.empty;
         allow_unstable_features = true;
+        ignore_string_methods = !ignore_string_methods;
       }
   in
   let tcopt =